diff --git a/completion/data_object.php b/completion/data_object.php
index 9d862ba914a..73837ad2a42 100644
--- a/completion/data_object.php
+++ b/completion/data_object.php
@@ -213,6 +213,7 @@ abstract class data_object {
 
         $wheresql = array();
 
+        $dbparams = array();
         foreach ($params as $var=>$value) {
             if (!in_array($var, $instance->required_fields) and !array_key_exists($var, $instance->optional_fields)) {
                 continue;
@@ -221,7 +222,7 @@ abstract class data_object {
                 $wheresql[] = " $var IS NULL ";
             } else {
                 $wheresql[] = " $var = ? ";
-                $params[] = $value;
+                $dbparams[] = $value;
             }
         }
 
@@ -232,7 +233,7 @@ abstract class data_object {
         }
 
         global $DB;
-        if ($datas = $DB->get_records_select($table, $wheresql, $params)) {
+        if ($datas = $DB->get_records_select($table, $wheresql, $dbparams)) {
 
             $result = array();
             foreach($datas as $data) {